2 files changed, 201 insertions, 0 deletions
diff --git a/2023/go/internal/day_03/part_01/part_01.go b/2023/go/internal/day_03/part_01/part_01.go
new file mode 100644
index 0000000..49837b3
--- /dev/null
+++ b/2023/go/internal/day_03/part_01/part_01.go
@@ -0,0 +1,123 @@
+package part_01
+
+/**
+ * TRIED:
+ * 530923
+ */
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+const USE_SAMPLE = true
+
+func Solve() {
+	var content []byte
+	if USE_SAMPLE {
+		content, _ = os.ReadFile("../_input/day_03_part_01_sample.txt")
+	} else {
+		content, _ = os.ReadFile("../_input/day_03.txt")
+	}
+	lines := strings.Split(string(content), "\n")
+
+	validNumbers := walkLines(lines)
+
+	answer := 0
+	for _, number := range validNumbers {
+		answer += number
+	}
+
+	println(answer)
+}
+
+func walkLines(lines []string) []int {
+	var validNumbers []int
+
+	for y := 0; y < len(lines); y++ {
+		line := lines[y]
+
+		if line == "" || line == "\n" {
+			continue
+		}
+
+		// Counts as a symbol...
+		filteredLine := strings.ReplaceAll(line, "\r", "")
+
+		previousWasNumber := false
+		number := ""
+		for x := 0; x < len(filteredLine); x++ {
+			char := filteredLine[x]
+
+			_, err := strconv.Atoi(string(char))
+			isNumeric := err == nil
+
+			if isNumeric {
+				previousWasNumber = true
+				number += string(char)
+				continue
+			}
+
+			if !previousWasNumber {
+				continue
+			}
+
+			isValid := checkValidity(lines, x, y, len(number))
+			if isValid {
+				num, _ := strconv.Atoi(number)
+				validNumbers = append(validNumbers, num)
+			}
+
+			println(number)
+
+			previousWasNumber = false
+			number = ""
+		}
+	}
+
+	return validNumbers
+}
+
+// N = number
+// k = numOfDigits + 1
+// (x-k,y-1) (x-1,y-1) ( x ,y-1)
+// (x-k, y )     N     ( x , y )
+// (x-k,y+1) (x-1,y+1) ( x ,y+1)
+func checkValidity(lines []string, x int, y int, numOfDigits int) bool {
+
+	for i := max(y-1, 0); i <= y+1; i++ {
+
+		var debugLine string
+
+		for j := max(x-(numOfDigits+1), 0); j <= x; j++ {
+
+			if lineExists := len(lines) > i; !lineExists {
+				continue
+			}
+
+			if charExists := len(lines[i]) > j; !charExists {
+				continue
+			}
+
+			char := rune(lines[i][j])
+			debugLine += string(char)
+
+			if char == '.' {
+				continue
+			}
+
+			_, err := strconv.Atoi(string(char))
+			isNumeric := err == nil
+			if isNumeric {
+				continue
+			}
+
+			debugLine = "" //nolint:ineffassign // Only used for debugging and needs to be reset
+
+			return true
+		}
+	}
+
+	return false
+}
diff --git a/2023/go/internal/day_03/part_01/part_01_test.go b/2023/go/internal/day_03/part_01/part_01_test.go
new file mode 100644
index 0000000..a077fbd
--- /dev/null
+++ b/2023/go/internal/day_03/part_01/part_01_test.go
@@ -0,0 +1,78 @@
+package part_01
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestWalkLines(t *testing.T) {
+	lines := getSampleLines()
+	expected := 4361
+
+	validNumbers := walkLines(lines)
+
+	actual := 0
+	for _, number := range validNumbers {
+		actual += number
+	}
+
+	if actual != expected {
+		t.Errorf("Expected answer to be %d, got %d", expected, actual)
+	}
+}
+
+func TestCheckValidity(t *testing.T) {
+	lines := getSampleLines()
+
+	tests := []struct {
+		x        int
+		y        int
+		length   int
+		expected bool
+	}{
+		{3, 0, 3, true},  // 467
+		{8, 0, 3, false}, // 114
+		{9, 0, 1, false}, //   3 - Added to check for '\r' counting as a symbol
+		{4, 2, 2, true},  //  35
+		{9, 2, 3, true},  // 633
+		{9, 3, 1, false}, //   3 - Added to check if number continues to next line
+		{3, 4, 3, true},  // 617
+		{9, 5, 2, false}, //  58
+		{5, 6, 3, true},  // 592
+		{9, 7, 3, true},  // 775
+		{4, 9, 3, true},  // 664
+		{8, 9, 3, true},  // 598
+	}
+
+	for _, test := range tests {
+		actual := checkValidity(lines, test.x, test.y, test.length)
+
+		if actual != test.expected {
+			t.Errorf("Expected %d, %d, %d to be %t, got %t", test.x, test.y, test.length, test.expected, actual)
+		}
+	}
+}
+
+func getSampleLines() []string {
+	contents, err := os.ReadFile("../../../../_input/day_03_part_01_sample.txt")
+	if err != nil {
+		panic(err)
+	}
+
+	lines := strings.Split(string(contents), "\n")
+
+	var filteredLines []string
+	for _, line := range lines {
+		if line == "" || line == "\n" {
+			continue
+		}
+
+		// Counts as a symbol...
+		filteredLine := strings.ReplaceAll(line, "\r", "")
+
+		filteredLines = append(filteredLines, filteredLine)
+	}
+
+	return filteredLines
+}